A semiconductor device comprising a metal-oxide-semiconductor field-effect transistor well controllably brings the work function of a gate electrode close to the intrinsic mid gap energy of silicon, thereby lowering the concentration of impurities in a channel. By this, the deterioration of carrier mobility is prevented and a metal-oxide-semiconductor field-effect transistor is obtained. A gate electrode has a multi-layer structure of a p-type polycrystalline or a single-crystalline germanium film 3 and a low resistance conductive film 4.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A semiconductor device, comprising: a silicon substrate, a gate insulation film on the silicon substrate, a germanium film on the gate insulation film, a polysilicon film on the germanium film, and a transition metal nitride in direct contact with the polysilicon film, wherein p-type impurities are doped into the germanium film, and a range of concentration of the p-type impurities is about 10 17 to 10 20 cm 3 .
2. The semiconductor device according to claim 1 , wherein the germanium film includes at least one of a single-crystalline germanium film, a polycrystalline germanium film and an amorphous germanium film.
3. A semiconductor device, comprising: a substrate; an insulation film on the substrate; a silicon film on the insulation fil; a gate insulation film on the silicon film; a germanium film on the gate insulation film; a polysilicon film on the germanium film; and a transition metal nitride in direct contact with the polysilicon film, wherein p-type impurities are doped into the germanium film, and a range of concentration of the p-type impurities is about 10 17 to 10 20 cm 3 .
4. The semiconductor device according to claim 3 , wherein the germanium film includes at least one of a single-crystalline germanium film, a polycrystalline germanium and an amorphous germanium film.
5. The semiconductor device according to claim 1 , wherein p-type impurities are doped into a channel region, and a range of concentration of the P-type impurities is 10 17 to 10 20 cm 3 , and wherein a resistance of the substrate is 14 to 22 /cm.
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February 23, 2001
September 7, 2004
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